Magnetic materials, the intend of the present book is very important in many fields of science, engineering and technology. This book contains introduction to the field of magnetic materials specially soft magnetic materials, its synthesis parameters, spinel structure formation and also their optical and magnetic properties. The book will supply fundamental knowledge on spinels and cover broad range of related topics. It would give great pleasure to the authors if the content of this book can provide useful information which may be used to inspire the readers to new research directions.